1. Field of the Invention
This invention relates to hydraulic torque converters, and more specifically to means for directly coupling the pump and turbine members of a torque converter so that power may be transmitted therethrough either hydrodynamically or mechanically. The torque converter according to the invention is contemplated for use, for example, in the power trains of motor vehicles including motorcycles.
2. Description of the Prior Art
As is well known, the torque multiplication of a hydraulic torque converter is maximum at zero output speed, that is, when the turbine member is stalled. As the output speed approaches the input or engine speed, the ratio of the output to the input torque falls off until, at a certain ratio of output to input speeds which usually lies between 0.65 and 0.85, the torque ratio becomes unity. This is referred to as the clutch point because under this condition the torque converter acts merely as a fluid coupling or clutch, with no torque conversion and no torque reaction on its stationary reactor member.
Should the speed ratio be allowed to exceed that at the clutch point, the torque ratio would drop below unity and torque reaction on the reactor would be negative. In order to avoid this the mode of operation may be changed from torque conversion either to simple fluid coupling (with the reactor member mounted on a freewheel clutch) or to direct mechanical drive, as at the clutch point. The present invention is directed to the second mentioned alternative.
Heretofore, for providing direct mechanical drive through a torque converter, a clutch has been employed for directly coupling either the input and output shafts, or the pump and turbine members, of the converter. In either case the clutch together with various associated means is located externally of the members or elements of the converter, so that its overall mass is materially increased. Such bulky converters are not suitable for use, for example, on small sized motor vehicles including motorcycles where economy in installation space is of paramount importance.